5,778 research outputs found
Bidirectional Shift in the Cornu Ammonis 3 Pyramidal Dendritic Organization Following Brief Stress
No full textThe negative impact of chronic stress at the structure of apical dendrite branches of cornu ammonis 3 (CA3) pyramidal neurons is well established. However, there is no information available on the CA3 dendritic organization related to short-lasting stress, which suffices to produce long-term habituation or sensitization of anxiety behaviors and neuroendocrine responses. Here, we tested the effects evoked by brief stress on the arrangements of CA3 pyramidal neuron dendrites, and the activity-dependent properties of the commissural-associational (C/A) excitatory postsynaptic potentials (EPSPs). Adult male rats were socially defeated followed by 3 weeks without further treatment or as comparison exposed to a regimen of a social defeat every second day for the same time period. We assessed CA3 pyramidal neurons with somatic whole-cell recording and neurobiotin application in acute hippocampal slices. The results from morphometric analysis of post hoc reconstructions demonstrated that CA3 dendrites from repeatedly stressed rats were reduced in surface area and length selectively at the apical cone (70% of control, approximately 280 µm from the soma). Brief stress, however, produced a similar decrease in apical dendritic length (77% of control, approximately 400 µm from the soma), accompanied by an increased length (167% of control) and branch complexity at the basal cone. The structural changes of the dendrites significantly influenced signal propagation by shortening the onset latency of EPSPs and increasing input resistance (r=0.45, P<0.01), of which the first was significantly changed in repeatedly stressed animals. Both brief and repeated stress long-lastingly impaired long-term potentiation of C/A synapses to a similar degree (P<0.05). These data indicate that the geometric plasticity of CA3 dendrites is dissociated from repetition of aversive experiences. A double social conflict suffices to drive a dynamic reorganization, by site-selective elimination and de novo growth of dendrite branches over the course of weeks after the actual experience.
Whose story is it anyway? The ethics of narration and the narration of ethics in Summertime and Die Sneeuslaper
No full textIncludes bibliographical references.This dissertation analyses and compares the narrative strategies in J.M. Coetzee’s Summertime and Marlene van Niekerk’s Die sneeuslaper and considers the implications of these strategies for the authors’ exploration of the ethics of writing. Much has been written about the literary oeuvres of both Coetzee and Van Niekerk, including studies of the translations of Van Niekerk’s Afrikaans novels into English. There are few “interlingual” comparative studies of contemporary works in Afrikaans and English, however, and certainly none to my knowledge which compares the work of Coetzee and Van Niekerk. My contribution to the conversation about Coetzee’s and Van Niekerk’s work, but also to an increasingly multilingual and interconnected South African literary criticism, will be a comparison of one recent work by each of these two authors, written in English and Afrikaans respectively. I draw on the theories of Bakhtin, Barthes and Levinas to consider the ethical dimension of texts in which “double-voicedness”, a questioning not only of existence, but of the self is fore grounded in the content and narrative structure; where there is a shift in focus from the author to the reader (“the birth of the reader”) and “utterances” are made with the response of “the other” in mind
Vasopressinergic modulation of stress responses in the central amygdala of the Roman high-avoidance and low-avoidance rat
No full textThe central nucleus of the amygdala (CEA) is selectively involved in the passive component of the behavioral (immobility) and the accompanying parasympathetic response during conditioned, stressful environmental challenges. Vasopressinergic mechanisms in the brain seem to play a role in these stress responses. The effects of the neuropeptides arginine-8-vasopressin (AVP) and oxytocin (OXT) on modulating CEA activity during conditioned stress of inescapable footshock were studied in male Roman high-avoidance (RHA/Verh) and low-avoidance (RLA/Verh) rats, psychogenetically selected on the basis of shuttle-box acquisition behavior. In RLA/Verh rats, the cardiac and behavioral responses to the conditioned emotional stressor were bradycardia and immobility, suggesting an important role for the CEA in these rats. The RHA/Verh rats, however, failed to show any change in heart rate or immobility in response to a conditioned stress situation. The low dose of AVP (20 pg) in the CEA of conscious RLA/Verh rats caused an enhancement of the stress-induced bradycardiac and immobility response. However, the high dose of AVP (2 ng) and OXT (200 pg) attenuated the bradycardiac and immobility responses in the RLA/Verh rats. Infusion of AVP and OXT in the RHA/Verh rats failed to induce any change in heart rate nr immobility. Binding studies revealed that the AVP receptor selectively binds AVP with high affinity. In contrast, the OXT receptor recognizes both AVP and OXT with a similar (but lower) affinity. This suggests that the behavioral and autonomic responses of the high dose of AVP may be caused by OXT receptor stimulation. In conclusion, on the basis of the present results one may hypothesize that CEA differences in AVP and OXT innervation and/or receptor densities may contribute to the differences in coping strategy found in these animals.
"The day of the great writer is gone for ever": Author surrogacy in Martin Amis’s Money and J.M. Coetzee’s Summertime.
No full textThis study focuses on the use of author surrogacy in the novels Money: A Suicide Note by Martin Amis and Summertime: Scenes from Provincial Life by J.M. Coetzee. It addresses the connection between their use of author surrogacy and their comments on what scholars classify as the postmodern cultural condition. Both authors have written themselves into their novels with a different purpose but both used strikingly similar themes to incorporate this purpose, although the stress on these themes varies. Authorial power, the distinction between the real and the imagined, and the fading line between high- and lowbrow culture are examples of the topics discussed in this study with regards to author surrogacy and the postmodern cultural condition. This study concludes that, through their use of author surrogacy, J.M. Coetzee mainly aims to critique, while Martin Amis satirises postmodern culture.
Keywords: Amis, author surrogacy, authorial power, Coetzee, fact-fiction distinction, high- and lowbrow culture, postmodern cultural condition
O doświadczeniu obcości języka w twórczości J.M. Coetzeego. Słowo wstępne
No full textThe present foreword refers to the address delivered by J.M. Coetzee on the occasion of conferring upon him by the University of Silesia the doctor honoris causa degree. Particular attention is paid to his thoughts on the role of English in the world of today. The author of the foreword shows that reflection on language in general and its role in moulding one’s identity in present in the Nobel laureate’s works, including his most recent novels. Further into the foreword, the author briefly discusses text reprinted in Śląskie Studia Polonistyczne: the already mentioned address by J.M. Coetzee, the conversation with the Author, and an article devoted to his works written by Robert Kusek.The present foreword refers to the address delivered by J.M. Coetzee on the occasion of conferring upon him by the University of Silesia the doctor honoris causa degree. Particular attention is paid to his thoughts on the role of English in the world of today. The author of the foreword shows that reflection on language in general and its role in moulding one’s identity in present in the Nobel laureate’s works, including his most recent novels. Further into the foreword, the author briefly discusses text reprinted in Śląskie Studia Polonistyczne: the already mentioned address by J.M. Coetzee, the conversation with the Author, and an article devoted to his works written by Robert Kusek
O doświadczeniu obcości języka w twórczości J.M. Coetzeego : słowo wstępne
No full textThe present foreword refers to the address delivered by J.M. Coetzee on the occasion of conferring upon him by the University of Silesia the doctor honoris causa degree. Particular attention is paid to his thoughts on the role of English in the world of today. The author of the foreword shows that reflection on language in general and its role in moulding one’s identity in present in the Nobel laureate’s works, including his most recent novels. Further into the foreword, the author briefly discusses text reprinted in Śląskie Studia Polonistyczne: the already mentioned address by J.M. Coetzee, the conversation with the Author, and an article devoted to his works written by Robert Kusek
The Corticomedial Amygdala and Learning in an Agonistic Situation in the Rat
No full textSocial agonistic behaviour of intact male rats is strongly reduced by the experience of defeat by a dominant male conspecific. Small electrolytic lesions in the corticomedial amygdala strongly affected this behavioural change due to defeat. No effects of the lesions were observed before and during the defeat. Some learning is still possible in corticomedial amygdala lesioned animals. A comparison of the effects of lesions made before the defeat with lesions made after the defeat revealed that the lesions primarily produce a retention deficit in social learning.
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